The volume required would be the minimum amount you can achieve while still allowing the piston to stay closed, and travel far enough to open. So, as flinger said, do your best to make it as small as possible.

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Last edited by BC Pneumatics on Fri May 23, 2008 7:17 pm, edited 1 time in total.

For most people, yes. There is a point at which the volume could not physically decrease without the diameter shrinking, thus not providing the force needed to keep the piston sealed. This point doesn't exist from a strictly mathematical standpoint, nor would it likely be encountered here, but something in my very rigid mind makes me consider things like this situation, and mention them in posts.

And add a lil extra traveling to be sure.
Traveling 1/8" too much isnt bad, but traveling 1/16th" too less is.
The extra travel also makes you have less problems with bouncing problems.
Some pistons may bounce back a short way.

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Till the day I'm dieing, I'll keep them spuddies flying, 'cause I can!

That doesn't look right because the units are wrong. You're adding three lengths and getting a volume. That ain't possible. (Dimensional analysis to the rescue!)

Shouldn't it be, for a solid cylindrical piston;
pilot volume V<sub>1</sub> = (distance piston must move)(area of piston)
The "distance piston must move" is generally taken to be at least 1/4 of the barrel diameter.

For a cylindrical piston open at one end;
pilot volume V<sub>2</sub> = V<sub>1</sub> + internal volume of piston.

If there is a bumper then you need to know what the gas volume is in the bumper region.
pilot volume V<sub>3</sub>= V<sub>2</sub> + gas volume in the bumper region

That doesn't look right because the units are wrong. You're adding three lengths and getting a volume. That ain't possible. (Dimensional analysis to the rescue!)

Shouldn't it be, for a solid cylindrical piston;pilot volume V<sub>1</sub> = (distance piston must move)(area of piston)The "distance piston must move" is generally taken to be at least 1/4 of the barrel diameter.

For a cylindrical piston open at one end;pilot volume V<sub>2</sub> = V<sub>1</sub> + internal volume of piston.

If there is a bumper then you need to know what the gas volume is in the bumper region.pilot volume V<sub>3</sub>= V<sub>2</sub> + gas volume in the bumper region